On 11/11/20 10:06 AM, Jitendra Loyal wrote: > Thanks Nikolay > > I read that but is there a way to meet the above requirement. And I will > like to add that IS NULL and IS NOT NULL should evaluate to true/false. > These operators are made for this and should not be returning NULL. >
This has nothing to do with IS [NOT] NULL, it's the first part of the expression (b = TRUE) causing trouble. Essentially, the constraint
(b = true) and (c is not null)
is evaluated in two steps. First we evaluate the two parts individually, and for (null, true) the results would look like this:
(b = true) => null (c is not null) => true
and then we combine those results using 'AND'
null AND true => null
which is considered as if the constraint matches. If you want to handle NULL for the first expression, you may do this, for example:
